Even with all the improvements in dish and laundry detergent formulations for washing dishes and laundry over the last twenty years, cleaning soiled dishes and laundry having certain types of stains remains problematic. Cleaning reusable plastic dishware can be particularly challenging. Plastic tubs having lids are commonly used for storing leftover food. Anyone who has stored food in such plastic containers has experienced the plastic becoming stained. This is because many foods contain natural and artificial dyes. Foods such as cherries and blueberries have red to blue anthocyanin dyes. Orange-red carotenoids such as lycopene and beta-carotene are found in tomatoes or carrots. Yellow curcuma dyes are found in curry and mustard. Of course, the above foods also on occasion end up spilled upon clothing articles, resulting in stains that are difficult to remove.
Conventional dish laundry detergent compositions include bleaching agents such as sodium percarbonate and use amine cobalt salt as a bleach catalyst. Some dish and laundry detergent formulations use sodium hypochlorite as a bleaching agent. Automatic dishwasher detergent composition formulations and laundry detergent formulations employing such bleaching agents have varying degrees of efficacy with such efficacy not always meeting consumer desires. Depending on the particular automatic dishwasher detergent composition being used, it is not uncommon for plastic food storage tubs to remain stained after washing. Similarly, sometimes stains on clothing are not removed to a satisfactory degree when washed in an automatic dishwasher.
Other benefit active ingredients might be desirable in automatic dishwasher detergent and laundry detergent compositions. For example, it might be desirable to include benefit active ingredients such as stain removers, bactericides, and active ingredients for eliminating endospores on dish, cooking ware, and clothing.
There are many benefit active ingredients that can conceivably be included in dish and laundry detergent compositions. Of course, there are many technical challenges to integrating such benefit active ingredients into commercially viable dishwasher detergent compositions. Many benefit active ingredients may not be chemically stable in powder, liquid, or gel formulations. Dish and laundry detergent compositions having certain benefit active ingredients may not be physically stable. Some benefit active ingredients may not be environmentally stable. For instance, changes in temperature and humidity may have adverse effects on the composition. Further, some benefit active ingredients may be incompatible with other components of dishwasher detergent compositions.
An alternative approach for enabling the inclusion of certain benefit active ingredients in dishwasher detergent compositions is the use of photo-activated chemistry. For instance, micronized titanium dioxide in water can be activated by light to become a bleaching system. Photoactivators such as phthalocyanines and naphthalocyanines, including sulphonated zinc phthalocyanine, can be effective as a photo bleaching agent and antimicrobial agent. Similarly, such benefit active ingredients can be provided in a composition separate from a fully formulated dish or laundry detergent.
One bather to employing photoactive chemistry in dish and laundry detergents is the necessity of irradiating the cleaning composition within the dishwasher or laundry washing machine during the cycle. Dishwashing and laundry washing machines can be provided with interior lights at the time of manufacture. However, if an efficacious detergent that includes photoactive chemistry is developed, the vast majority of appliances that are presently in consumers households are without such interior lighting. It is unlikely that consumers will purchase a new appliance to take advantage of a detergent that employs photoactive chemistry. In view of that, even if a developer of detergents develops a fantastic breakthrough composition employing photochemistry, only a limited fraction of consumers will be able to see the benefit. The volume of dishwasher detergent composition required to supply the limited fraction of consumers who might be willing to purchase an appliance having interior lighting may not be a justifiable business proposition. Nor may it be attractive for a business to wait over time, perhaps many years, until new models of dishwashers having the interior lighting make their way into consumers' households.
With these limitations in mind, there is a continuing unaddressed needed for methods and devices that will provide consumers with the ability to take advantage of photoactive chemistry in dishwashing and laundry washing without the need to purchase a new expensive appliance having integral interior lighting.